1. Field of the Invention
The subject matter of the present invention pertains to a joystick apparatus for developing electrical signals representative of the location of a point in a two-dimensional coordinate system.
2. Description of the Prior Art
A joystick apparatus develops a first and a second electrical signal indicative of the location of a point in a two-dimensional coordinate system. The joystick apparatus includes a movable joystick fixed at one end and angularly movable with respect to said one end thereof, the angular position of the joystick with respect to a vertical line defining the point in the two-dimensional coordinate system, the joystick apparatus developing the electrical signals representative thereof. The joystick apparatus is typically used in conjunction with a cathode-ray tube (CRT) display and a digital computer to enter graphic data displayed on the CRT into the digital computer. The joystick apparatus of the prior art contained an excessively high number of component parts. In addition, the joystick apparatus was non-rebuildable. As a result, a high number of rejects resulted. Furthermore, when the joystick is parallel to the vertical line, the first and second electrical signals generated from the joystick apparatus should be zero, and the point should represent the origin of the two-dimensional coordinate system. However, when the joystick of the prior art was approximately parallel to the vertical line, non-zero electrical signals were developed. Therefore, the resultant point did not represent the origin of the two-dimensional coordinate system. In response to the non-zero electrical signals, the resultant point drifted in the two-dimensional coordinate system.